The present invention relates to a waste ink collecting device which collects waste ink discharged and/or sucked through a waste ink nozzle of a printhead of an inkjet printer.
Conventionally, in an inkjet printer for personal use, a waste ink collecting chamber is defined inside the main body of the inkjet printer to collect waste ink, which is discharged by or sucked from an printhead when cleaning of the printhead is performed, ink cartridges are to be exchanged and the like. The waste ink is dropped onto the waste ink collecting chamber accommodating ink absorbers for absorbing the dropped ink. Typically, in the inkjet printers for personal use, the amount of printing is relatively small, the quantity of the waste ink absorbed by the ink absorbers during its product life is relatively small. Therefore, the quantity of the waste ink throughout the product life of the printer hardly exceeds the capacity (i.e. absorbable quantity) of the ink absorber, and it is generally not necessary to exchange the ink absorber. Therefore, in the personal-use inkjet printer, the waste ink collecting chamber is configured such that the ink absorber is not replaced.
In a business-use inkjet printer whose printing amount is relatively large and/or in a commercial-use inkjet printer such as one for printing a poster or dress fabric having a relatively wide printing area, the frequency of cleaning operations increases.
That is, in the business-use inkjet printer, the quantity of the ink consumed is relatively large. Further, when the printing is carried out on the dress fabric, due to diversification of fabric material, various fabric dust may adhere on an inner surface of each nozzle of the printhead. Furthermore, the heat generated due to the increase of printing load causes air bubbles within the ink inside the printhead, which affects ejection of the ink from the nozzles of the printhead. Therefore, it becomes necessary to carry out the cleaning of the printhead frequently. As the frequency of the cleaning increases, the quantity of the waste ink increases.
An example of a conventional waste ink collecting device for such a business-use and/or commercial-use inkjet printer will be described with reference to FIG. 9.
FIG. 9 is a cross-sectional view of a conventional waste ink collecting device 20. The waste ink collecting device 20 is configured such that the waste ink is dropped from the above portion thereof. At a time when the cleaning of a printhead (not shown) is carried out, the waste ink discharged from or sucked through nozzles of the printhead is fed to a discharging tube 23, and is further fed to a dropping tube 25 via a discharging pump 24 (the discharging tube may be omitted when the waste ink is dropped by gravity). As shown in FIG. 9, the dropping tube 25 is located immediately above an opening 26 formed on a waste ink tank 21. The waste ink collecting device 20 has the waste ink tank 21 and an ink absorber 22 made of material having a high absorption rate such as felt, bonded-fiber fabric or the like. The ink absorber 22 is formed to have a shape of a substantially rectangular solid so as to fit the inner shape of the waste ink tank 21. As shown in FIG. 9, the waste ink dropped from the dropping tube 25 directly strikes the ink absorber 22 through the opening 26, and is absorbed by the ink absorber 22. Although not shown in FIG. 9, the waste ink tank 21 may be provided with an openable cover structure so that the ink absorber 22 can be exchanged with a new one when necessary.
FIG. 10 shows another example of a conventional waste ink collecting device, which is disclosed in Japanese Patent Provisional Publication No. HEI 09-085965. In FIG. 10, the members similar to those in FIG. 9 have the same reference numbers. In this example, the upper surface of the ink absorber 22 is inclined, and the waste ink from the dropping tube 26 drop on the higher side (i.e., right-hand side in FIG. 10) of the ink absorber 22. In this example, since the ink absorber 22 is configured such that a portion where the waste ink drops is higher (thicker) and a portion further therefrom is lower (thinner), the ink dropped on the higher portion is absorbed by the higher portion initially, and then permeates/spreads to lower portions gradually.
In the first example (FIG. 9), the waste ink permeates the waste ink absorber 22 downward from a position at which the waste ink drops. Since the upper surface of the ink absorber 22 extends substantially horizontally, the dropped ink hardly permeates the ink absorber 22 in the horizontal direction. Thus, according to the configuration of the first example, the entire volume of the ink absorber 22 is not used efficiently, and the waste ink concentrates at portions within a certain area centering around the portion where the ink drops.
In the second example (FIG. 10), since the upper surface of the ink absorber 22 inclines with respect to the horizontal direction, the dropped ink permeates along the upper surface of the ink absorber 22. However, in this configuration, since the portion at which the ink drops is located at the end portion of the ink absorber 22, a distance from the position where the ink drops to the end portion of the ink absorber 22 is relatively long. Accordingly, the end portion of the ink absorber 22 tends to absorb the ink insufficiently. Therefore, also in this case, the entire volume of the ink absorber 22 may not be used efficiently.
Further to the above defect, according to the structure of the first and second examples, the upper surface of the ink absorber 22 faces the opening 26. Therefore, the waste ink absorbed by the ink absorber 22 may easily evaporate from the upper surface of the ink absorber, in particular, at a portion facing the opening 26. When the ink evaporates, the residual material of the waste ink is condensed, which weaken the absorption property of the ink absorber 22.